The one that stands alone
by C-artist
Summary: A new person shows up, mysterious and rude. But this person it going to play a big role in the Vongola family members' life. Especially for a certain person. O/OC
1. The mysterious one

**Katekyo Hitman Reborn!**

The one who stands alone!

**#The mysterious one#**

"Reborn-san…I assume you needed me?"

"You are the one indeed…Listen…"

--

"Why do you keep hanging out with us, baseball-idiot?" Gokudera said.

"Geez, Gokudera-kun, don't start again! He's as much as a friend as you are, so do-" Tsuna was interrupted by a kunai hitting the ground an inch from his left foot. "IIIEEE!"

"Tsuna!" Yamamoto and Gokudera yelled and the last one turned around, drawing out his dynamite and throwing it in the direction the weapon came. It was a wall that got hit and was ruined, the smoke circled up in the sky and a dark silhouette was seen behind it.

"Thanks for the smoke, it made my entrance a lot better…" The dark voice came for the guy behind the smoke and he stepped forwards. The guy was clad in black, an raincoat reaching the middle of his thighs a black shirt with some silver necklaces, black jeans and shoes and last but not least a black hat, which reminded Tsuna of Reborn's , though the band around it wasn't orange but a light shade of grey. It shielded his face as he held the front of it down with his right hand, but his dark hair which was tight in a loose tail was seen as it reached the middle of his back.

"TEME! How dare you attack Juudaime, you bastard! I'll kill you!" The dynamite expert yelled as he was about to run to the fellow.

"Gokudera-kun, don't… he's probably just one of Reborn-san's hired guys…like that death-faking guy." Tsuna stated while holding his friend back and dragging him the other way, but Gokudera shook the hand off and attacked the dark guy, throwing his dynamite to him already.

The guy blocked them by hitting them with his senbon and then showed off his speed, appearing in a split second behind Gokudera. He leaned over and whispered in a soft voice, "You know, you look a lot hotter when you are standing still, Hayato-san."

A shiver shoot through the silver-haired man's back and his knees got weak for a second, but he gathered himself, turned and threw a heck of a lot dynamite to his enemy. He simply dodged them and waited for the next attack.

Yamamoto was hesitating if he should enter the fight, finally decided that he could at least distract the guy so Gokudera had more time. He grabbed a baseball from his bag and threw it full-speed at the fellows head, hoping to knock him out. It was seen and dodged again with a simple movement and an instant he disappeared and then appeared in front of Yamamoto, his face close to the other's. "You're skilled, though, wouldn't you want to use that skilled hand for something completely different, Takeshi-san?" he said in a husky and soft voice.

Yamamoto went red, he knew exactly what the man meant since it was clearly heard in the way he said it and a shiver ran up his spine too. Though, his quick reflexes reacted on his own and grabbed his katana and took a swing at the man. And again it was dodged and the man took his distance.

Another attack was launched, this time from Ryohei, fist first he ran at the guy and while he tried to avoid it with a jump it stroke the side of his stomach. "EXTREME!" Ryohei yelled, but it was to soon. Again the mystic man disappeared and appeared behind him and spoke in a soft voice, "Not that extreme are you, joining in when most of the battle is over and then only being able to give me a simple scratch. More like Extremely embarrassing… onii-san." And it hit Ryohei hard. It was true what the fellow said. At least that's what he himself thought. His never failing lion-punch merely hit and that was something Ryohei couldn't imagine. It was the reason his mind went completely blank and he just stood there, trying to figure out what went wrong.

The man now took his appearance in front of Tsuna and spoke to him in a normal voice. "Aren't you feeling bad? All you're precious friends are fighting a battle and you're the only one who's utterly useless. Maybe you really are No Good-Tsuna… And that's supposed to be the next Vongola boss? Pathetic, don't you think, Tsunayoshi-san?" This triggered Tsuna to become so angry that he threw his fist at the guy, aiming at his jaw. But it missed as the man simply took a step backwards. Tsuna looked at the man, then to the ground. He felt ashamed, he really couldn't do anything to help his friends, not unless Reborn was here, but of course his teacher was nowhere in sight.

Now the man walked backwards, turning at the last moment before getting hit by another load of dynamite from Gokudera. He didn't avoid it and when it exploded and smoke circled up in the sky again everyone got the hopes he was gone. Though, for Tsuna nothing goes as wanted, because behind the smokescreen were two figures seen. One small and on a podium, Reborn-san and the second the same mystic man as they just fought.

"REBORN-SAN!" Tsuna yelled.

"Ciaossu, Tsuna-kun." Reborn greeted.

"THAT BASTARD'S STILL THERE!" Gokudera yelled.

"Minna-san, I would like to introduce to you Kai-n-san, also known as Bull's-eye." Reborn pointed to the mystic man. The man smiled a little, a hand at the brim of his hat, keeping it down.

"Ara? _The _Bull's-eye? From the movies? The hero?" Tsuna completely forgot his shame and was now looking with admiring eyes at Kai-n.

"That idiot? He doesn't even look like me! I'm the one from the myths, but even the myths are wrong at most points…" He answered.

"You're the real one?! Kaikkoii!" Tsuna was nearly jumping with excitement.

"Cut it out, kid. I'm not here to be worshipped." Kai-n answered annoyed.

"Kai-n-san is one unique mafia. He's no boss, no hitman, no subordinate or part of a famiglia, but a mafia nonetheless.

"Tsuna-kun, Kai-n-san is going to be your trainer." Reborn broke in.

"But, I thought _you_ were my teacher?"

"I am. But there's a difference between trainer and teacher, Tsuna-kun. And Kai-n-san is going to train you and the others on fighting abilities."

"I thought we had our own teachers?" Ryohei replied.

"There are many styles when it comes to fighting and I think you are all ready for a new one. The more styles, the stronger you'll be and less predictable. Now can one of you tell me, what is his fighting style?"

There fell a silence, because none could recall the answer. All had been to busy with his own part of the battle and the things said. Maybe that was an answer, was what Gokudera thought.

"He said something to all of us." He said.

"What did he say to you, Gokudera-kun?" Reborn replied, Kai-n smiled devilish, they had it hard while it was just so simple.

"He said I looked a lot hotter when I would stand still." He answered, a bit reluctant, because it might be a compliment, it was said by a male and you could imagine how weird that is.

"And to you, Yamamoto-kun?"

"…" He had opened his mouth, but his face got red all over again and he stared at the ground, it was just too embarrassing.

Reborn looked at Kai-n, who shrugged and replied like it was the most obvious thing he could say, "I just said he could use his skilled hand for other things."

"Is that true, Yamamoto-kun?" Reborn watched at the swordsman who nodded, then he turned to Sasagawa. "And to you?"

"That I was extremely embarrassing." Ryohei replied with a voice as if he was very disappointed with himself.

"And Tsuna-kun?"

"That I was really no good for anyone…" He said in the same voice as Ryohei.

Kai-n finally lifted his hat, a smile still on his face. His silvery-grey eyes locked on Reborn, asking silent permission for speaking. The Mafia infant took notice of it and gave a nod as soon as he said the next. "Kai-n-san works with weaknesses. Kai-n-san, plea-"

"Wait a minute! What you said to me wasn't really a weakness, was it?!" Gokudera interrupted him.

"It wasn't, but your ear is one of the most sensitive spots of your body." Kai-n replied calmly. "Causing you to think it was offending and putting all your anger in an attack."

"Then what about the others?" He tried to defend himself.

" Yamamoto-san is smart, his brain jumps to conclusions quick. But when you know how, you can confuse the brain to think in a certain way. I tricked him by saying otherwise harmless words with an sexual intonation, causing him to jump to such conclusion.

"Sasagawa-san has a huge confidence in himself. That is a strong point, but with the right actions or words you can bring it down. He knows what he does and when it goes wrong, add up to that that I mocked him and he breaks down.

"And Sawada-san cares a lot about what other people think about him, so when you tell him what has been told to him a thousand times it calls up embarrassment and anger, especially when it is some stranger telling it." Kai-n paused. All were silent, stubbornly agreeing to the explanation. "When provoked verbally or physically it triggers an emotion. In Gokudera-san's and Sawada-san's case it triggers anger, causing you to put all your power in a powerful attack, but an attack is only successful when it is aimed, has power and when you have a goal with it. 'Anger'-attacks often leak aiming or are blind, like some sort of reflex. In case of Yamamoto-san and Sasagawa-san it triggers shame, causing one to act blindly and the other to black-out."

Again a long silence where everyone seemed to agree to the explanation. And they should, Kai-n was about their age, a year older in fact, but Kai-n was a mafia for almost eight years now. He had always worked with this style and it always worked out, because it was a style that wasn't predictable at all.

"But why did you attack Sawada-san?" Yamamoto finally asked.

"Come on! You call that an attack? I'm not called Bull's-eye for no reason, idiot! It was an inch from his left foot, if I had wanted to kill him than I would have aimed at his heart, and it would have been bull's-eye!"

"And there is my next question… Did you notice something about Kai-n-san's fighting?" Reborn watched as frowns appeared on Tsuna and his friends faces. It was silent for another few minutes, before he took the word again. "He didn't attack, except for the first strike, the kunai. Furthermore, he only dodged and blocked your attacks. Kai-n…?"

"When you don't want or need to fight, or your hurt, this is the way to stay unharmed. You don't have to focus on your own attacks, so your mind is 100 focused on the enemy. That's why, when you are only dodging and blocking, you have the chance to avoid injuries and even scratches."

"And that's why he's going to be your trainer." Reborn finished.


	2. Thrusting the stranger

**# Thrusting the stranger #**

"Can't believe I actually took the job… I don't even get paid. And yet I have to be at Sawada-kun's house with that bunch of kids and that annoying brat…" Kai-n mumbled as he walked leisurely on his way to Tsuna's home. Then he saw someone, namely Gokudera, walk from one of the front gardens. "Oh, great, there you have him already…" Kai-n tried to walk past him, hoping the kid wouldn't recognize him, but that was in vain.

" Kai-n-san." He acknowledged the other, Kai-n nodded as reply. Then they walked for a few minutes in silence. "… How did you know all our weaknesses?"

"Almost all people, especially men, have a sensitive spot at the ear, idiot." He replied.

"But the others?"

"Something called observation, moron. Though, it was only one day… most of you guys are really obvious."

"How, if you were hiding I would definitely found out…"

"You're the only one that would…But I have my ways…"

It was getting annoying… like Gokudera was radiating a 'you're-suspicious-so-tell-everything-about-yourself'-aura. "What do you want? You're going to learn everything today, so shut up and wait."

"…" a silence fell again, a few minutes, and as they went around a corner Gokudera spoke up again. "Tell me your weakness…."

'_Geez, why does he needs to know…Well, I'll just show him something…Hope he doesn't tell too much…' _Kai-n slipped a blue package from his sleeve, a sign on it showed an arrow going from big to small. He opened it and drew out a long blue needle. The package was hidden back in his sleeve and he placed the needle against his wrist before pushing it in his skin. A small, soundless gasp and the needle was completely in. A poof and blue smoke appeared. Gokudera was startled as suddenly Kai-n was disappeared.

"Whahaha, everyone is scared of me! Me, the ruler of the sand-box!" A child's voice came from the smoke, which slowly faded. "Ara, Yuri-kun, where are you?"

"K-Kai-n-sama?!" Gokudera sputtered.

"That's me! Though, it's only Kai...Who are you, sir?" The child, dressed in black like his older self, chirped happily and curious. "And do you know where I am? I suddenly appeared here while I was playing happily at the playground with Yuri-kun…"

"I-I'm Gokudera Hayato…I believe you are in the future…" He replied confused.

"Oh, well I don't see a letter so I guess I don't have to do something for my future me… Good, now I have more time to see this world!" Kai-n jumped a little and skipped to the side of the sidewalk, where all the cars raced by at the other side of a low fence. He stared fascinated at the cars and the street, then he suddenly grinned and wanted to step on the road.

"Oi, what are you doing?!" Gokudera snapped as his hand grabbed the back of the kid's raincoat, before the kid would get overrun by a car.

"I wanted to see the street from the other side!" The child whined while trying to kick the guy who held him. It didn't work though, Gokudera held him tightly against his chest.

"No, you don't! It's dangerous, do you want to die?!" Kai-n stopped with struggling and turned his head from him, setting up an irritated face, puffing his cheeks and shutting his eyes tightly. Though, it didn't last long, since kids forget little fights quickly.

"Did you know I'm ticklish?" The child chirped happily again, turning his face back. Gokudera was looking the other way.

"Oh, really?" He said annoyed. Kai-n nodded furiously.

"In my neck! Onii-san says it's an sensitive spot that brings great pleasure, but I don't really know what that means so I'll just say I'm ticklish!" Then the time-limit had arrived and another poof and a lot of blue smoke told Gokudera that the older Kai-n was back. So did the extra weight on his shoulders and the extra space needed between his arms. "Oh God, what did I do to be in this position…?"

"Kai-n-san?!" Gokudera finally able to see the person in his arms, the smoke finally faded.

"Well, are you going to tell me or what?"

"Y-you turned into a kid and wanted to cross that street." He answered, pointing with his eyes to the street.

"And you held me even when I was passing the five minutes, idiot!"

"How should I know there was a time-limit?!" Gokudera yelled, they were still holding each other but none of them seemed to notice.

"Don't tell me you don't now the 10-year bazooka?!"

"That turns you ten year older, you de-aged!"

"That's the same kind of thing, idiot! And why are you still holding me!"

"Says the one who is holding me! Now shut up or I'll blow you to pieces!" Gokudera, having a headache for most of the day, was getting annoyed and then used the information he just got from the kid. He stroked Kai-n's neck, sending shivers through his body.

"God, no! I didn't tell you I have a s-"

"That you were ticklish? Yes, you did." Gokudera said triumphantly as the other let him go immediately.

"Alright, now you know, just shut up, will you?" Kai-n replied, continuing the way.

Silence ruled over their walk towards Tsuna's house, though, Gokudera broke it again as it had just reached five minutes. "What did you mean with onii-san?"

"…" A reply stayed out.

"What did you mean with it?"

They neared a little alley, dark and empty, that was on the route so they cornered and that's where, when Gokudera wanted to ask his attention again, Kai-n turned, grabbed him at his collar and smashed him against a wall. "Do you wanna know?! Well, I've got news for you! They're dead! Killed! And the best part? The murderer hasn't been caught, yet!" He hissed angrily in Gokudera's face. "And now you know another weakness of me, happy? Tell me one of yours!"

"Let me go, idiot!" He said as he draw out his dynamite. "I'll blow you to pieces!"

"You won't or rather can't, you know how I dodge them. Now, tell me!" Kai-n replied dangerously as he knocked the dynamite out of his hands. "And let it be something good, something equal to my secret."

"…" He was hesitating, his position wasn't very good and his secrets all big. Though, he had to settle for something, a lie would be found out, he knew and it wasn't helping that the fist at his throat was tightening his grip. But something about this black-clad man was telling him he could thrust him, that he wouldn't tell anyone. Probably, because his life was some kind of similar to this person. "Fine, I…I- I'm gay…" He finally spoke, casting his eyes downwards and to his left. Apparently, it was good enough to be a secret, because he felt the hand around his throat loosen and finally saw the guy step back, visibly trying to calm his anger.

"Really…? Well, that's good enough." Kai-n said, a faint shimmering in his eyes, whatever that could mean…

--

At Tsuna's house it was crowded, though, Tsuna and Reborn were still watching for people outside the gate. The first getting pretty inpatient, the second sitting leisurely on the wall. Sometimes Kyoko and Haru would ask if they saw the two persons that were expected, but then they got an negative answer and went inside again to play with Lambo and I-pin.

"Why are they so late? Gokudera-kun's always at least five minutes early! And Kai-n? What's causing him to be late, aren't teachers obliged to be on time?" Tsuna muttered. And there was the 10ft green hammer that landed on his head. "OW! That hurts, REBORN!

"Be patient, Dame-Tsuna! Something must have gotten up…"

"Don't call me that! And what? Gokudera-kun would never let me wait!" Tsuna whined, clutching his head with his hands.

--

"Juudaime! Can you please forgive me for being so late?!" Gokudera came running to Tsuna and threw himself on his knees. "That bastard caused it! But I'm so sorry!"

Tsuna looked in shock at the silver haired man at his feet. Really, like he was some kind of boss… wait, he was the tenth Vongola boss… Just great… "It's okay! Don't be sorry, it wasn't your fault! I'm just happy you came!" He rattled.

"Waru, Sawada-san. Got some trouble with that brat." Kai-n answered with a voice like he didn't cared much. Tsuna looked at him, but waved it off, though Kai-n got a furious glare from the silver-haired kid still on his knees.

"Are you ready to train this lot of thrash?" Reborn asked pointing to the noisy crowd inside and around the house.

"Always, Reborn-san…Always." Kai-n answered with a sadistic smirk on his face.

"Then let's start." Reborn jumped on his shoulder and walked into the garden.

--


End file.
